In a speaker to be used for a small-sized device such as a cellular phone, a circular coil having a relatively small size, which is obtained by winding a relatively thin wire in a circular fashion, is conventionally used. As a method of manufacturing the circular coil described above, a winding apparatus for winding a wire for a coil around a core having a circular cross section is known (JP1997-148168A). In the winding apparatus, the wire wound around the core into a coil shape is removed from the core to obtain the circular coil having a desired diameter.
In recent years, a speaker having an oval or oblong cross section is often used as the speaker to be used for the small-sized devices. For the speaker having the oval or oblong cross section, a non-circular coil having an oblong, oval, or ellipsoidal cross section is used.